Air mixer for ventilating systems



Oct. 15, 1940. HQCQLUCUTT 2,217,944

AIR MIXER 'FOR VENTILATING SYSTEMS Filed July 14, 1937 t6 INVENTOR. H H-Callzcuzl Patented Oct. 15, 1940 UNITED STATES AIR MIXER FOR VENTILATINGSYSTEMS Earl H. Collicutt, New York, N. Y., assignor to The AerofuserCompany, Inc., New York, N. Y.

Application July 14, 1937, Serial No. 153,470 6 Claims. (CI. 98-38)'This invention relates to ventilating systems in which a building isfurnished with air ducts leading from the exterior or from a central airblower to the rooms of the building, and the main object is to provide amixer for each room which operates to draw air from a supply duct andfrom the room into a mixing chamber from which the mixed air is blownback into the room.

A further object is to provide an apparatus and method whereby the airof a room may be l e-conditioned without objectionable draft or rapidair movement. A further object is to provide an apparatus of thischaracter which may be housed within a wall or ceiling of a roomdirectly in the air duct lineand without projection into the room, andwhich apparatus will be light in weight, easily installed, inexpensivein construction, noiseless in operation, and capable of ornamentalfinish at or about the wall or ceiling opening. My improved method ofair re-conditioning consists in simultaneously creating suction at'opposite openings in a. chamber to draw air from a fresh air supply andfrom a room, causing such, air currents to become mixed within thechamber, and ejecting the mixed or re-conditione'd air into the room atan angle away from the current of air being drawn into the mixer fromthe room. g

In carrying my method into effect I employ in the preferred form a mixercomprising a chamber, preferably in the form of a shell or dome hav-'ing a small opening at the top and entirely open at its base, and whichis preferably mounted within a junction box in an air duct line with thebase of the dome flush with the wall or ceiling,and within this dome ishoused a pair of fan-wheel blowers rotated by a small electric motormounted upon or withinthe dome. These blowers are preferably mountedtogether in axial alignment, the upper blower, that is, the bloweradjacent the opening at the top of the dome, drawing air from the airduct line and blowing it into the dome, and the lower blower drawing airfrom the room and blowing it into the dome, and the action of the twoblowers causing'the two air currents to circulate within the domewhereby the air drawn from the room is re-conditioned by mixture withthefresh air drawn from the air duct line. Due to the dome-like chamber themixed air as it is caused to circulate is driven downward and out of thechamber at its base and into the room, and for the purpose of direct ingthis air current I provide beneath the blowers and preferably within thebase opening of the cally opposite points.

lugs ll, four being shown, projecting radially 5 dome a series ofconcentric louvres in the form of a grille, the central louvresdirecting the air current from the room into the lower blower, and theouter louvres being placed at an angle to deflect the re-conditioned aircurrent at an angle 5 away from the incoming air current from the room.

My invention is illustrated in the accompanying drawing, in which-Figure 1 is a vertical section illustrating an air 10 duct line within awall or above the ceiling of a room, a junction-box, and my air mixerwithin the junction-box comprisingan air dome having an air intake atthe top, the mixed air outlet'at the bottom having a grille withlouvresfor directing the air currents, a motor and fan-wheel blowers,the latter being partly broken away to show the partition between theblowers.

Figure 2 a horizontal section on the line 22 of Figure l.

Figure 3 a plan view looking upward into the grille; and

Figure 4 a central vertical section of the fanwheel blowers showing thevanes of the blower which draws air from the room set at an angle 25 tothe axis of the wheel instead of parallel therewith.

Referring to the drawing, 1 and 2 indicate the air duct line, and 3 thejunction box which may be square as shown in Figure 2, or of any other30 shape, and open at the bottom as seen in Figure 1, The junction boxhas ports 4 at which ducts l and 2 are attached in any suitable manner,and the box has a flange 5 which is secured to a frame 6 of wood orother suitable material. The ducts, '85 junction box and supportingframe 6 are let into the wall or ceiling as indicated in Figure 1, andbelow the frame and attached thereto is the usual metal or other lath Ion which the plaster 8 is laid in the usual manner. Within the 40 frame6 and set so that its outer rim will be flush with plaster 8 is a metalring 9 which is secured to frame 6 by woodscrews H! at diametri- Ring 9has a number of toward the center of the ring and having the undersidebevelled as seen in Figure 1.

The mixer comprises a chamber I2, which is preferably of dome-shape, amotor l3, fan-wheel blowers l4 and I5, and the grille IS. The dome I2 isa sheet metal shell with a circular opening I! at the top and having anoutward flare l8 at the base terminating'in a circular flange l9 whichseats against and covers the lower edge of supporting ring 9. The flarel8 has the same an- 66 gle as the angular louvres of the grille,hereinafter referred to, which fits the bevel on the underside of lugs II where the dome is secured by screws 20 to the ring 9. At the top thedome has secured.

thereto a set of brackets 2| to which a collar 22 is brazed or otherwiserigidly secured. The brackets and collar are drilled and tapped forsetscrews 23. The inner diameter of the collar is such as to loosely fltthe housing of motor I3 which is set within the collar to the desireddepth with its shaft in vertical position and secured in adjustedposition by the set-screws 23. It will be noted that the motor bodyprojects into the dome through opening II, thereby reducing the heightof the mixing chamber, and that the diameter of the opening is such asto provide sufficient clearance for the entrance of air into the domefrom the junction-box 3.

The blowers I 4 and I5 are represented as fan-' wheels of the usualtype, each preferably having a base plate 24, angularly set vanes 25,and top ring 26. The two blowers are preferably secured together withthe base plates 24 back-toback as seen in Figure 1, thus providing aclosed partition between them, and are provided with a hub 21,preferably within the wheel I4 for attachment to the motor shaft and towhich it is secured by set-screw 28. By this arrangement of wheels I4and I5 and supporting hub 21 it is possible to project the body andshaft of the motor within wheel I4 thereby reducing the height of theentire apparatus. It will be noted that the height of the dome from theinner edge of flare I8 is only suflicient to give clearance to the rims26 of wheels I4 and I5 between the grille and dome.

In Figure 4 the vanes 25 of the fan-wheel I5 are shown set at an inwardangle toward the axis of the wheel instead of parallel to the wheel axisas in Figure 1. With this arrangement thediameters of the concentriccylindrical louvres 29 will be decreased in order that the larger ringof the louvres 29 will not direct air outside of the wheel, but entirelywithin the rim 26 of the wheel. I find that this arrangement provides amuch greater pull of air from the room and hence more rapidly mixes theroom air with fresh air drawn from ducts i-2 through the top of the domeby fan-wheel it. If desired both fan-wheels may have the vanes set at aninward angle at the rims 26, or the combination may be varied by settingeither set of vanes at an outward angle at the rim 26 to decrease thepull of either wheel.

Below the fan-wheel blowers and seated within the flare I8 of the domeis the grille I6 which is composed of two series of concentric rings.This grille is preferably seated within the base of the dome to reducethe height of the mixer and so that the grille may be flush with theceiling, although in practice the grille may project therefrom forornamental or other reasons without affecting the operativeness of themixer. The central series of louvres 29 constitute short cylindricallouvres, the larger ring of the series being of a diameter preferablyequal to or less than the inner diameter of wheel ring 26 of blower I5so as to direct the air current to the interior of the wheel. The outerseries of louvres or rings 30 are in the form of short truncated conesof approximately a forty-five degree angle with the smaller diameterinward, and the smaller ring of this series preferably making closecontact at its upper edge with the upper edge of the larger of the rings29 so that no air will be drawn up around the outer circumference ofsuch ring 29.

The louvre rings 29 and 39 are perforated at diametrically oppositepoints to receive supporting rods 3| to which the rings are brazed orotherwise secured to maintain them in concentric spaced relation. Therods project beyond the outer ring 30 and are adapted to seat in groovedlugs 32 brazed to the flare I9 of the dome as best seen in Figure 1. Toplace the grillein position it is inserted into the dome opening so thatthe ends of rods 3| will pass by the lugs and then the grille is rotatedto bring the ends of the rods over the lugs and allowed to drop in placein the lug grooves. This arrangement permits easy removal of the grillefor cleaning both the grille, the blowers and the inside of the dome.For removal of the mixer from the junction-box, screws are removed andthe dome with the motor, blowers and grille allowed to drop from thejunctionbox.

In the operation of the mixer, the air flowing through ducts l2 is drawndown through opening I1 at the top of the dome and into the fan- .wheelI4 by the action of its vanes and is driven out between the vanes intothe space under the dome surrounding wheels I4 and I5, and at the sametime air from the room is drawn up through louvres 29 into fan-wheel I5and is driven out between its vanes 25 into the lower part of the dome.The circulation of the two air currents within the dome due to theaction of vanes 25 causes the two air currents to mix and there-conditioned air is driven out through louvres 30, the angle of thelouvres deflecting the current of reconditioned air away from the axialcenter of the mixer so as not to mix with or affect the current of airbeing drawn into the mixer from the room.

It will be understood that a single fan-wheel without the base plate ordividing partition may be employed and that the operation will besimilar to the double fan-wheel arrangement, although for most purposeswill not be as efficient. When a single fan-wheel with open top andbottom is employed, the action of the vanes due to the rotation of thewheel will operate to eject air peripherally between the vanes, therebyreducing the volume or pressure at or about the wheel axis and cause airto flow axially into the wheel through the open ends and the two aircurrents become mixed and are ejected by the action of the vanes. Thesame action takes place when two fan-wheels with a dividing partitionare employed, but I have found that with a dividing partition themovement of the air currents and mixing in the surrounding chamber ismore effective.

It will also be understood that the proportioning of the air mixing,that is, the rate of pull from the fresh air ducts and from the room forreconditioning of the room air, may be varied by proportioning the size,diameter or height, or angular-set of the. vanes of the two fan-wheels-or fan-wheel sections, thereby varying the air flow through thefan-wheels. Or the mixture may be proportioned by varying the relativediameters of the intake openings of the mixing chamber.

It will also be observed that by the use of my improved air mixer, themixing of fresh cold air with the heated air within a room is avoided,and that thereby objectionable effects of cold drafts within a room dueto the common method of forcing fresh air into a room is avoided, andthat my method of withdrawing heated air from a room, mixing it withfresh cold air in a mixin chamber, and distributing such re-conditionedair in a room'avoids the necessity for providing extra feed ductscommonly employed in ventilating systems for minimizing drafts of coldair into a room.

It will also be observed that my improved method of air conditioning isespecially well adapted for rooms having low ceilings in that noperceptible air drafts are present, even at points within one footvertically below the center of the mixer. This is due to the fact thatthe warm room air is exhausted from the room by a fan-wheel axiallythereof and elected peripherally into the mixing chamber from which there-conditioned air is ejected at a deflected angle due to the louvresand thereby causing the re-conditioned air to spread outward into theroom above the warm air of the room and away fromthe axial center of themixer.

What I claim is:

1. In a ventilating system, the combination with an air duct, of a mixercomprising a chamber open at opposite ends and having imperioratesloping walls, the small end of the chamber communicating with the airduct and the large .end opening intoa room, a centrifugal blower withinsaid chamber operating to draw air axially into the blowersimultaneously from the air duct and room and to drive the two aircurrents peripherally therefrom and cause said air currents to circulateand mix within the chamber and to force the mixed air outward along thesloping walls of the chamber concentrically to the axis of the blowerinto the room.

2. In a ventilating system, the combination with an air duct, of a mixercomprising a chamber open at opposite ends and having imperiorate sidewalls, the opening at one end communicating with the-air duct and theother opening directly into a room, a centrifugal blower within thechamber operating to draw air axially into the blower simultaneouslyfrom the air duct and room and to drive the two air currentsperipherally therefrom and cause said air currents to circulate and mixwithin the chamber, and to force the mixed air outward from the chamberinto the room, and a deflector at the room end of the chamber fordeflecting the mixed air ejected from the chamber away from. the axialcenter of the chamber.

3. In a ventilating system, the combination with an air duct, of a mixercomprising'a circular chamber open at opposite ends and havingimperforate side walls, one opening being an inlet communicating withsaid duct and the other opening directly into a room, a multivan'edfanwheel rotating within said chamber and operating to draw air axiallyinto the wheel simultaneously from the duct and room and ejecting thetwo air currents peripherally therefrom and opening of the chamber, thecentral deflector being arranged direct the room air'axially into thefan-wheel, and the outer deflector serving to deflect the mixed airejected from the chamber laterally away from the axial center of themixer chamber.

4. In a ventilating system, the combination with an air duct, of a mixercomprising a chamber positioned adjacent said duct and communicatingtherewith and having an opening into a room, a motor mounted on saidchamber, a pair of fan-wheel blowers within the chamber and rotated bysaid motor, one of said blowers hav ing its vanes set to draw air fromsaid duct into the chamber and the vanes of the other blower being setto ,draw air from the room into the chamber and whereby the tw aircurrents are mixed within the chamber, ahd a grille over the the roomopening of the mixing chamber composed of concentric ring louvres, thecentral rings of the grille being short cylindrical sections fordirecting the air drawn from the room,

shaped casing adjacent said duct and communicating therewith through anopening at thetop of the dome and entirely, open at the base, a motormounted on said dome and projecting through said opening at the top, apair of fanwheel blowers mounted together on the motor shaft and havinga closed dividing partition, one of said blowers having its vanes set todraw air from said duct through said opening at the top of the dome, andthe vanes of the other blower being set to draw air from. a room intosaid dome, and whereby the two air currents are mixed within the dome,and a'set of concentric ring louvres in the form of a grflle over thebase a opening of the dome, the central rings of the grille being shortcylindrical sections for directing the air drawn from the room, and theouter rings being short truncated conic sections for deflecting themixed air driven from the dome outward away from the axial center of themixer,

8. In an air mixer, the combination of a domeshaped chamber having anopening at the top and a larger opening at the base, a motor mounted onsaid chamber, a fan-wheel blower within said chamber divided into twosections by a closed partition, one section drawing air through thetopopening and the other section through the base opening, and bothsections delivering air to the surrounding space in said chamber andcausing same to mix, a hub within one of the blower sections formounting the blower on the motor shaft, and a series of louvres in theform of a grille removably attached to the base of the dome, and havinga central set of louvres for directing air into the adjacent blowersection, and an outer set of louvres set at an angle for deflecting themixed air driven from the cham- EARL H. COLIJCUIT.

